Based on the capture force field potential model and the adiabatic invariant proposed by Bates, adopting improved average dipole orientation (IADO) theory, the force constants between transition metal ions and benzene...Based on the capture force field potential model and the adiabatic invariant proposed by Bates, adopting improved average dipole orientation (IADO) theory, the force constants between transition metal ions and benzene (bz) and also a series of inner-sphere reoganization energy (REin) were calculated. The reasons for the differences between theoretical predictions and experimental results were discussed.展开更多
Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversi...Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversion(TTA-UC), respectively. It turned out that the pyridine cation served as a mask for the excited state of the sensitizer, the triplet states of S-2 and S-3 were significantly quenched by photo-induced electron transfer(PET) with phosphorescence quantum yield quenched from 24.4% for S-4 to 9.3% for S-3,and therefore, both S-2 and S-3 led to negligible UC emissions when traditional annihilator DPA was used as the annihilator. Delightfully, when supramolecular annihilator A-1 and A-2 were employed to include the pyridine cation, PET was significantly inhibited and the triplet states of the sensitizers were activated,TTA-UC emission was therefore boosted. The UC quantum yield of A-2/S-3 system was up to 130 times higher than that of DPA/S-3 system, and the UC emission was switchable by the addition of competitive vips.展开更多
Humic acid(HA) as a natural reducing ligand was employed to accelerate the Fenton and Fenton-like processes, however, the potential role of photosensitivity was overlooked. This research showed that HA exhibits more s...Humic acid(HA) as a natural reducing ligand was employed to accelerate the Fenton and Fenton-like processes, however, the potential role of photosensitivity was overlooked. This research showed that HA exhibits more significant promotion for levofloxacin(LVF) degradation under light conditions compared to darkness. The study also proposed a mechanism involving complexation and photosensitization interactions. A strong inhibitor of ethylenediaminetetraacetic acid confirmed that the formation of organic-iron complexes was crucial. Firstly, it was proposed that complexed iron has a lower redox potential than free iron, which may be responsible for accelerating electron transfer from iron to peroxydisulfate(PDS). The density functional theory(DFT) calculations confirmed that complexed iron has a lower reaction energy barrier for PDS activation. Additionally, the excited state substances(^(*)HA and ^(*)LVF) can transfer electrons to Fe(Ⅲ) and PDS, and the generation of HA/LVF-Fe(Ⅲ)-PDS can accelerate this process. These findings could offer fresh perspectives on the combined elimination of contaminants through natural organic compounds and light exposure.展开更多
Based on a non-equilibrium kinetic extraction technique,the complexation kinetics of diethylenetriamine-pentaacetic acid(DTPA)with rare earth(RE)ions was investigated with different adding sequences of DTPA.The result...Based on a non-equilibrium kinetic extraction technique,the complexation kinetics of diethylenetriamine-pentaacetic acid(DTPA)with rare earth(RE)ions was investigated with different adding sequences of DTPA.The results indicated that the separation factors ofβTm/Er andβY/Er were higher when adding DTPA at the start of extraction than those before extraction.The extraction order for Y,Er and Tm was Tm>Y>Er.The root of discrepancy in complexation kinetics of Y,Er and Tm ions with DTPA and the enhanced kinetic separation mechanism were elucidated from the forward complex formation and reverse dissociation rates by the stopped-flow spectrophotometric technique.The apparent complexation rate constants began to decrease gradually with the increase of aqueous pH,while increased with increasing DTPA concentration.The emergence of extraction priority order as Tm>Y>Er was verified according to the calculated reaction kinetic constants of Y,Er and Tm at different pH values.展开更多
The authors regret that an error in Fig.3E in this article was found while we reviewing the published data.An inadvertent mistake occurred in the process of assembling images.The picture of the Ms215μg/mL group was w...The authors regret that an error in Fig.3E in this article was found while we reviewing the published data.An inadvertent mistake occurred in the process of assembling images.The picture of the Ms215μg/mL group was wrongly placed.展开更多
Dear Editor,We present a case of acute zonal occult outer retinopathy(AZOOR)complex in a myopic patient with angioid streaks(ASs).A 19-year-old female has been experiencing visual field defects in her left eye for mor...Dear Editor,We present a case of acute zonal occult outer retinopathy(AZOOR)complex in a myopic patient with angioid streaks(ASs).A 19-year-old female has been experiencing visual field defects in her left eye for more than 3y.She was diagnosed with ASs and choroiditis at a local hospital.She has a seven-year history of bilateral high myopia.A fundus examination confirmed the presence of ASs and myopic fundus changes in both eyes.Multimodal imaging revealed an AZOOR complex in the left eye.展开更多
Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current ev...Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current evidence on diagnostic protocols and management strategies,highlighting optimal approaches and emerging trends.Initial care emphasizes soft tissue assessment,often guided by the Tscherne classification,and fracture classification systems.External fixation may be required in open injuries,while early open reduction and internal fixation within six days is linked to improved outcomes.Minimally invasive techniques for the lateral malleolus,including intramedullary nailing and locking plates,are effective,while medial malleolus fractures are commonly managed with screw fixation or tension-band wiring.Posterior malleolus fragments involving more than 25%of the articular surface usually warrant fixation.Alternatives to syndesmotic screws,such as cortical buttons or high-strength sutures,reduce the need for secondary procedures.Arthroscopic-assisted open reduction and internal fixation benefits younger,active patients by enabling concurrent management of intra-articular and ligamentous injuries.Postoperative care prioritizes early weight-bearing and validated functional scores.Despite advances,complications remain common,and further research is needed to refine surgical strategies and improve outcomes.展开更多
In the present study, we investigated the complexation of risperidone with hydroxypropyl-β-cyclodextrin （HP-β-CD） in aqueous solution due to the poor water solubility and low oral bioavailability of risperidone in...In the present study, we investigated the complexation of risperidone with hydroxypropyl-β-cyclodextrin （HP-β-CD） in aqueous solution due to the poor water solubility and low oral bioavailability of risperidone in humans. The effect of temperature on the complexation was examined, and thermodynamic parameters of the complexation process, such as Gibbs free energy change （AG）, enthalpy change （AH） and entropy change （AS）, were also explored. Meantime, the solid dispersion of risperidone with HP-β-CD was prepared and confirmed by Fourier IR spectroscopy and X-ray diffractometry. The experimental results suggested that the complex of the drug with HP-β-CD at a molar ratio of 1：1 could form in aqueous solution, and the complexation was an endothermic and entropy-driven process. The risperidone-HP-β-CD solid dispersion exhibited a remarkable improvement in the dissolution rate of the drug. This might be attributed to the amorphous state, the enhanced wettability as well as the complex formation of the drug with HP-β-CD in aqueous solution.展开更多
Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and trans...Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.展开更多
The coordination reactions of Cu（Ⅱ） and Ni（Ⅱ） with acid alizarine blue B （AABB） in the presence of cetyltrimethylammonium bromide （CTAB） micelle were investigated using the microsurface adsorptionspectral co...The coordination reactions of Cu（Ⅱ） and Ni（Ⅱ） with acid alizarine blue B （AABB） in the presence of cetyltrimethylammonium bromide （CTAB） micelle were investigated using the microsurface adsorptionspectral correction technique （MSASC）. The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu（Ⅱ） or Ni（Ⅱ）and AABB. The binding ratio of AABB to CTAB was 1：2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB：Cu and AABB：Ni were 1：1 and 1：2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.展开更多
The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and t...The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..展开更多
Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface cha...Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface charge composition and layer-structure of solid-solution interface for the classical 1-pK and 2-pK models. In addition, the fundamental concept and relations of the new models, i. e., multi-site complexation (MUSIC) and charge- distribution (CD) MUSIC models were described as well. To avoid misuse or abuse, it must be emphasized that the applicability and limitation for each model should be considered carefully when selecting the concerned model(s). In addition, some new powerful techniques for surface characterization and analysis applied to model establishment and modification were also briefly introduced.展开更多
The inclusion complexes of poorly water-soluble cephalosporin, cefuroxime axetil(CFA), were prepared with β-cyclodextrin(βCD) with or without addition of L-arginine(ARG) to improve its physicochemical properties. We...The inclusion complexes of poorly water-soluble cephalosporin, cefuroxime axetil(CFA), were prepared with β-cyclodextrin(βCD) with or without addition of L-arginine(ARG) to improve its physicochemical properties. We also investigated the effect of ARG on complexation efficiency(CE) of βCD towards CFA in an aqueous medium through phase solubility behaviour according to Higuchi and Connors. Although phase solubility studies showed AL(linear) type of solubility curve in presence and absence of ARG, the CE and association constant(Ks) of βCD towards CFA were significantly promoted in presence of ARG,justifying its use as a ternary component. The solid systems of CFA with βCD were obtained by spray drying technique with or without incorporation of ARG and characterized by differential scanning calorimetry(DSC), X-ray powder diffractometry(XRPD), scanning electron microscopy(SEM), and saturation solubility and dissolution studies. The molecular modeling studies provided a better insight into geometry and inclusion mode of CFA inside βCD cavity. The solubility and dissolution rate of CFA were significantly improved upon complexation with βCD as compared to CFA alone. However, ternary system incorporated with ARG performed better than binary system in physicochemical evaluation. In conclusion, ARG could be exploited as a ternary component to improve the physicochemical properties of CFA via βCD complexation.展开更多
The effect of temperature-responsive solution behavior of PNIPAM-b-PPEOMA-b-PNIPAM on its inclusion complexation with α-cyclodextrin was studied. The triblock polymer was prepared by reversible addition-fragmentation...The effect of temperature-responsive solution behavior of PNIPAM-b-PPEOMA-b-PNIPAM on its inclusion complexation with α-cyclodextrin was studied. The triblock polymer was prepared by reversible addition-fragmentation chain transfer （RAFT） polymerization and formed inclusion complexes （ICs） after selective threading of the PEO segment of the triblock polymer through the cavities of α-CD units. For comparison, PPEOMA homopolymer was prepared and the inclusion complexation with α-CD was also studied. The ICs were prepared with a-CD when the polymer was in different conformations by changing the temperature, and the formed ICs were characterized by XRD, ^1H-NMR, TGA and DSC. The solutions of the ICs show temperature-responsive clear/turbid transition or fluidic emulsion/gel transition depending on the concentration of the α-CD added, and the stoichiometry determined by ^1H-NMR and TGA indicates that the stoichiometry of EO to α-CD of the resulted ICs increases with increasing of temperature.展开更多
Using three designed peptides with precisely-controlled charge density and three types of DNAs with different length and flexibility, the effect of charge density on the formation of PEC was studied. Highly charged（K...Using three designed peptides with precisely-controlled charge density and three types of DNAs with different length and flexibility, the effect of charge density on the formation of PEC was studied. Highly charged（KKKK）5 interacts strongly with 21 bp ds DNA to form large complex, followed by precipitation; while the medium charged（KGKG）5 only form complex with 21 bp ds DNA at proper ＋/- charge ratios; and no prominent complex between weakly charged（KGGG）5 and 21 bp ds DNA is observed at the same conditions. Similar trend is observed when the peptides form complex with 2000 bp DNA or 21 nt ssD NA. It is also found that the complex formed by adding peptide to DNA is in random coil conformation, but the complex prepared by the inverse order is in molten globule state. Re-dissolution of the complex occurs only when DNA is added to peptides with similar or shorter length.展开更多
A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the sour...A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the source of Al_(30).The PAC_(30)was prepared under conditions of total aluminum concentration 0.1 mol/L and OH^-/Al ratio 2.2 to obtain the highest content of Al_(30).A precipitation/metathesis method,organic solvent precipitation method and organic complexation method were examined to separate and purify Al_(30).It was found that only by the organic complexation method could high purity Al_(30)products be obtained in large yield economically.In the experiments,benzoic acid was used as the coordinating reagent to decompose the main impurity AlO_4Al_(12)(OH)_(24)(H_2O)_(12)^(7+)(Al_(13)),and the Al_(30)product could be obtained by precipitation and metathesis operations.It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr.The Al_(30)product was characterized by Ferron assay,^(27)Al-NMR,SEM,XRD and TGA.The results showed that the purity of the Al_(30)product could exceed 92%.展开更多
An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexa- tion reaction between cefixime and palladi...An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexa- tion reaction between cefixime and palladium ion in the presence of acidic buffer solution （pH 3） in ethanol-distilled water medium at room temperature. The complex absorbed maximally at 352 nm. Beer＇s law is obeyed in the working concentration range of 2.5-35 μg/mL with apparent molar absorptivity of 1.015×104 L/mol cm and Sandell＇s sensitivity of 0.001 μg/cm2/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.175 and 0.583μg/mL, respectively. The effect of common excipients used as additives has been studied in the determination of cefixime. The proposed method has been successfully applied for the determina- tion of cefixime in pharmaceutical formulations. The results obtained by the proposed method were statistically compared with the reference method using t and F values and found no significant difference between the two methods.展开更多
A series of monomethoxy poly（ethylene glycol） （mPEG） grafted copolyglutamates （PmPEGs） were synthesized through ring-opening polymerization （ROP） followed by click chemistry. Supramolecular hydrogels based on ...A series of monomethoxy poly（ethylene glycol） （mPEG） grafted copolyglutamates （PmPEGs） were synthesized through ring-opening polymerization （ROP） followed by click chemistry. Supramolecular hydrogels based on polymer inclusion complexes （ICs） between PmPEG and α-cyclodextriri （α-CD） were prepared in aqueous solution. The rheological measurements indicated their gelation properties were affected by several factors including the mPEG length, graft density and the sample concentration. These hydrogels displayed thermo-sensitive gel-sol transition under appropriate conditions due to the reversible mPEG and α-CD inclusion complexation. These hydrogels also showed pH-sensitive behavior due to the deprotonate of carboxylic acid side groups. The ICs formation of a channel-type crystalline structure induced gelation mechanism was verified by various techniques. In vitro cytotoxicity assays demonstrated that the supramolecular hydrogels are nontoxic and cytocompatible.展开更多
A novel method for the separation and reclamation of vanadium and chromium from acidic solution was proposed. The principle for the separation is based on selective complexation. In specific, V(V) can be complexated b...A novel method for the separation and reclamation of vanadium and chromium from acidic solution was proposed. The principle for the separation is based on selective complexation. In specific, V(V) can be complexated by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(Ⅲ) remained in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(Ⅲ)-bearing solution can be reached by decomplexation and neutralization, respectively. The kinetics of the complexation reaction was studied. In addition, the precipitation ratio of vanadium reached 97% and the loss of chromium was less than 4% after process optimization. The complexing agent could be regenerated with a high ratio of 99.5%. The method was successfully applied to treating chromium-vanadium-bearing slag produced in conventional vanadium production industry. Vanadium and chromium could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%.展开更多
Accumulation of toxic ions in leachate is one factor limiting bioleaching applications. The effect of fluoride ions on the growth of bioleaching microorganisms has been extensively emphasized. In this study, HF is fou...Accumulation of toxic ions in leachate is one factor limiting bioleaching applications. The effect of fluoride ions on the growth of bioleaching microorganisms has been extensively emphasized. In this study, HF is found to be the toxic form of fluoride that affects the bacterial activity under acidic conditions. The added aluminum could compete with H^+ to complex with F-, thus significantly decrease the concentration of HF and finally reduce the toxicity of fluoride to bacteria. When F^-/Al^(3+)concentration ratio is 0.5:1.0, Fe^(2+) oxidation rate could reach 0.167 g·L^(-1)·h^(-1), close to that of the biotic control group(0.195 g·L^(-1)·h^(-1)). The competitive complexation mechanism of fluoride by AlF_n^(3-n) results in stability constants of AlF_n^(3-n) complex(7.00) that are larger than those of HF(3.18). The F^-/Al^(3+) concentration ratio in the medium could affect the speciation of AlF_n^(3-n) complex.With the decrease in F^-/Al^(3+) concentration ratio, the coordination numbers of AlF_n^(3-n) decrease. Finally, the feasibility of fluoride detoxification by aluminum ion is verified. This work has meaningful implications for fluoride-containing bacterial bioleaching systems.展开更多
文摘Based on the capture force field potential model and the adiabatic invariant proposed by Bates, adopting improved average dipole orientation (IADO) theory, the force constants between transition metal ions and benzene (bz) and also a series of inner-sphere reoganization energy (REin) were calculated. The reasons for the differences between theoretical predictions and experimental results were discussed.
基金supported by the National Natural Science Foundation of China (Nos. 22171194, 21971169, 92056116 and 21871194)the Fundamental Research Funds for the Central Universities (No. 20826041D4117)the Science & Technology Department of Sichuan Province (Nos. 2022YFH0095 and 2021ZYD0052)。
文摘Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversion(TTA-UC), respectively. It turned out that the pyridine cation served as a mask for the excited state of the sensitizer, the triplet states of S-2 and S-3 were significantly quenched by photo-induced electron transfer(PET) with phosphorescence quantum yield quenched from 24.4% for S-4 to 9.3% for S-3,and therefore, both S-2 and S-3 led to negligible UC emissions when traditional annihilator DPA was used as the annihilator. Delightfully, when supramolecular annihilator A-1 and A-2 were employed to include the pyridine cation, PET was significantly inhibited and the triplet states of the sensitizers were activated,TTA-UC emission was therefore boosted. The UC quantum yield of A-2/S-3 system was up to 130 times higher than that of DPA/S-3 system, and the UC emission was switchable by the addition of competitive vips.
基金supported by the Natural Science Foundation of China (No. 42107073)Central Guidance for Local Science and Technology Development Fund Projects (No. 2024ZYD0030)+1 种基金Natural Science Foundation of Sichuan Province (No. 2024NSFSC0130)the Sichuan Science and Technology Program (No. 2024NSFTD0014)。
文摘Humic acid(HA) as a natural reducing ligand was employed to accelerate the Fenton and Fenton-like processes, however, the potential role of photosensitivity was overlooked. This research showed that HA exhibits more significant promotion for levofloxacin(LVF) degradation under light conditions compared to darkness. The study also proposed a mechanism involving complexation and photosensitization interactions. A strong inhibitor of ethylenediaminetetraacetic acid confirmed that the formation of organic-iron complexes was crucial. Firstly, it was proposed that complexed iron has a lower redox potential than free iron, which may be responsible for accelerating electron transfer from iron to peroxydisulfate(PDS). The density functional theory(DFT) calculations confirmed that complexed iron has a lower reaction energy barrier for PDS activation. Additionally, the excited state substances(^(*)HA and ^(*)LVF) can transfer electrons to Fe(Ⅲ) and PDS, and the generation of HA/LVF-Fe(Ⅲ)-PDS can accelerate this process. These findings could offer fresh perspectives on the combined elimination of contaminants through natural organic compounds and light exposure.
基金funded by Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources,China(No.2022IRERE206)financially supported by the National Natural Science Foundation of China(Nos.51904027,52074031)。
文摘Based on a non-equilibrium kinetic extraction technique,the complexation kinetics of diethylenetriamine-pentaacetic acid(DTPA)with rare earth(RE)ions was investigated with different adding sequences of DTPA.The results indicated that the separation factors ofβTm/Er andβY/Er were higher when adding DTPA at the start of extraction than those before extraction.The extraction order for Y,Er and Tm was Tm>Y>Er.The root of discrepancy in complexation kinetics of Y,Er and Tm ions with DTPA and the enhanced kinetic separation mechanism were elucidated from the forward complex formation and reverse dissociation rates by the stopped-flow spectrophotometric technique.The apparent complexation rate constants began to decrease gradually with the increase of aqueous pH,while increased with increasing DTPA concentration.The emergence of extraction priority order as Tm>Y>Er was verified according to the calculated reaction kinetic constants of Y,Er and Tm at different pH values.
文摘The authors regret that an error in Fig.3E in this article was found while we reviewing the published data.An inadvertent mistake occurred in the process of assembling images.The picture of the Ms215μg/mL group was wrongly placed.
基金Supported by the National Natural Science Foundation of China(No.82171073).
文摘Dear Editor,We present a case of acute zonal occult outer retinopathy(AZOOR)complex in a myopic patient with angioid streaks(ASs).A 19-year-old female has been experiencing visual field defects in her left eye for more than 3y.She was diagnosed with ASs and choroiditis at a local hospital.She has a seven-year history of bilateral high myopia.A fundus examination confirmed the presence of ASs and myopic fundus changes in both eyes.Multimodal imaging revealed an AZOOR complex in the left eye.
文摘Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current evidence on diagnostic protocols and management strategies,highlighting optimal approaches and emerging trends.Initial care emphasizes soft tissue assessment,often guided by the Tscherne classification,and fracture classification systems.External fixation may be required in open injuries,while early open reduction and internal fixation within six days is linked to improved outcomes.Minimally invasive techniques for the lateral malleolus,including intramedullary nailing and locking plates,are effective,while medial malleolus fractures are commonly managed with screw fixation or tension-band wiring.Posterior malleolus fragments involving more than 25%of the articular surface usually warrant fixation.Alternatives to syndesmotic screws,such as cortical buttons or high-strength sutures,reduce the need for secondary procedures.Arthroscopic-assisted open reduction and internal fixation benefits younger,active patients by enabling concurrent management of intra-articular and ligamentous injuries.Postoperative care prioritizes early weight-bearing and validated functional scores.Despite advances,complications remain common,and further research is needed to refine surgical strategies and improve outcomes.
基金Science and Technology Million Project of Inner Mongolia Medical University(Grant No.YKD2014KJBW012)
文摘In the present study, we investigated the complexation of risperidone with hydroxypropyl-β-cyclodextrin （HP-β-CD） in aqueous solution due to the poor water solubility and low oral bioavailability of risperidone in humans. The effect of temperature on the complexation was examined, and thermodynamic parameters of the complexation process, such as Gibbs free energy change （AG）, enthalpy change （AH） and entropy change （AS）, were also explored. Meantime, the solid dispersion of risperidone with HP-β-CD was prepared and confirmed by Fourier IR spectroscopy and X-ray diffractometry. The experimental results suggested that the complex of the drug with HP-β-CD at a molar ratio of 1：1 could form in aqueous solution, and the complexation was an endothermic and entropy-driven process. The risperidone-HP-β-CD solid dispersion exhibited a remarkable improvement in the dissolution rate of the drug. This might be attributed to the amorphous state, the enhanced wettability as well as the complex formation of the drug with HP-β-CD in aqueous solution.
基金financially supported jointly by Natural Science Foundation of Fujian Province of China(NO.2023J01227)Natural Science Foundation of Hebei Province(NO.D2020504003)Key Laboratory of Groundwater Remediation of Hebei Province and China Geological Survey(NO.SK202303).
文摘Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.
文摘The coordination reactions of Cu（Ⅱ） and Ni（Ⅱ） with acid alizarine blue B （AABB） in the presence of cetyltrimethylammonium bromide （CTAB） micelle were investigated using the microsurface adsorptionspectral correction technique （MSASC）. The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu（Ⅱ） or Ni（Ⅱ）and AABB. The binding ratio of AABB to CTAB was 1：2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB：Cu and AABB：Ni were 1：1 and 1：2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.
基金TheNationalNaturalScienceFoundationofChina (No .2 96 770 0 4)
文摘The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..
文摘Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface charge composition and layer-structure of solid-solution interface for the classical 1-pK and 2-pK models. In addition, the fundamental concept and relations of the new models, i. e., multi-site complexation (MUSIC) and charge- distribution (CD) MUSIC models were described as well. To avoid misuse or abuse, it must be emphasized that the applicability and limitation for each model should be considered carefully when selecting the concerned model(s). In addition, some new powerful techniques for surface characterization and analysis applied to model establishment and modification were also briefly introduced.
文摘The inclusion complexes of poorly water-soluble cephalosporin, cefuroxime axetil(CFA), were prepared with β-cyclodextrin(βCD) with or without addition of L-arginine(ARG) to improve its physicochemical properties. We also investigated the effect of ARG on complexation efficiency(CE) of βCD towards CFA in an aqueous medium through phase solubility behaviour according to Higuchi and Connors. Although phase solubility studies showed AL(linear) type of solubility curve in presence and absence of ARG, the CE and association constant(Ks) of βCD towards CFA were significantly promoted in presence of ARG,justifying its use as a ternary component. The solid systems of CFA with βCD were obtained by spray drying technique with or without incorporation of ARG and characterized by differential scanning calorimetry(DSC), X-ray powder diffractometry(XRPD), scanning electron microscopy(SEM), and saturation solubility and dissolution studies. The molecular modeling studies provided a better insight into geometry and inclusion mode of CFA inside βCD cavity. The solubility and dissolution rate of CFA were significantly improved upon complexation with βCD as compared to CFA alone. However, ternary system incorporated with ARG performed better than binary system in physicochemical evaluation. In conclusion, ARG could be exploited as a ternary component to improve the physicochemical properties of CFA via βCD complexation.
基金financially supported by the Hunan Normal University for providing start-up
文摘The effect of temperature-responsive solution behavior of PNIPAM-b-PPEOMA-b-PNIPAM on its inclusion complexation with α-cyclodextrin was studied. The triblock polymer was prepared by reversible addition-fragmentation chain transfer （RAFT） polymerization and formed inclusion complexes （ICs） after selective threading of the PEO segment of the triblock polymer through the cavities of α-CD units. For comparison, PPEOMA homopolymer was prepared and the inclusion complexation with α-CD was also studied. The ICs were prepared with a-CD when the polymer was in different conformations by changing the temperature, and the formed ICs were characterized by XRD, ^1H-NMR, TGA and DSC. The solutions of the ICs show temperature-responsive clear/turbid transition or fluidic emulsion/gel transition depending on the concentration of the α-CD added, and the stoichiometry determined by ^1H-NMR and TGA indicates that the stoichiometry of EO to α-CD of the resulted ICs increases with increasing of temperature.
基金supported by the National Natural Science Foundation of China(Nos.21174007 and 20990232)
文摘Using three designed peptides with precisely-controlled charge density and three types of DNAs with different length and flexibility, the effect of charge density on the formation of PEC was studied. Highly charged（KKKK）5 interacts strongly with 21 bp ds DNA to form large complex, followed by precipitation; while the medium charged（KGKG）5 only form complex with 21 bp ds DNA at proper ＋/- charge ratios; and no prominent complex between weakly charged（KGGG）5 and 21 bp ds DNA is observed at the same conditions. Similar trend is observed when the peptides form complex with 2000 bp DNA or 21 nt ssD NA. It is also found that the complex formed by adding peptide to DNA is in random coil conformation, but the complex prepared by the inverse order is in molten globule state. Re-dissolution of the complex occurs only when DNA is added to peptides with similar or shorter length.
基金supported by the National Natural Science Foundation of China (Nos. 21507149, 51338010)the National Water Pollution Control and Treatment Science and Technology Major Project (No. 2015ZX07406005-002)
文摘A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the source of Al_(30).The PAC_(30)was prepared under conditions of total aluminum concentration 0.1 mol/L and OH^-/Al ratio 2.2 to obtain the highest content of Al_(30).A precipitation/metathesis method,organic solvent precipitation method and organic complexation method were examined to separate and purify Al_(30).It was found that only by the organic complexation method could high purity Al_(30)products be obtained in large yield economically.In the experiments,benzoic acid was used as the coordinating reagent to decompose the main impurity AlO_4Al_(12)(OH)_(24)(H_2O)_(12)^(7+)(Al_(13)),and the Al_(30)product could be obtained by precipitation and metathesis operations.It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr.The Al_(30)product was characterized by Ferron assay,^(27)Al-NMR,SEM,XRD and TGA.The results showed that the purity of the Al_(30)product could exceed 92%.
文摘An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexa- tion reaction between cefixime and palladium ion in the presence of acidic buffer solution （pH 3） in ethanol-distilled water medium at room temperature. The complex absorbed maximally at 352 nm. Beer＇s law is obeyed in the working concentration range of 2.5-35 μg/mL with apparent molar absorptivity of 1.015×104 L/mol cm and Sandell＇s sensitivity of 0.001 μg/cm2/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.175 and 0.583μg/mL, respectively. The effect of common excipients used as additives has been studied in the determination of cefixime. The proposed method has been successfully applied for the determina- tion of cefixime in pharmaceutical formulations. The results obtained by the proposed method were statistically compared with the reference method using t and F values and found no significant difference between the two methods.
基金financially supported by the National Natural Science Fund for Distinguished Young Scholars(No.51225306)the National Natural Science Foundation of China(No.21434008)
文摘A series of monomethoxy poly（ethylene glycol） （mPEG） grafted copolyglutamates （PmPEGs） were synthesized through ring-opening polymerization （ROP） followed by click chemistry. Supramolecular hydrogels based on polymer inclusion complexes （ICs） between PmPEG and α-cyclodextriri （α-CD） were prepared in aqueous solution. The rheological measurements indicated their gelation properties were affected by several factors including the mPEG length, graft density and the sample concentration. These hydrogels displayed thermo-sensitive gel-sol transition under appropriate conditions due to the reversible mPEG and α-CD inclusion complexation. These hydrogels also showed pH-sensitive behavior due to the deprotonate of carboxylic acid side groups. The ICs formation of a channel-type crystalline structure induced gelation mechanism was verified by various techniques. In vitro cytotoxicity assays demonstrated that the supramolecular hydrogels are nontoxic and cytocompatible.
基金Project(51674230) supported by the National Natural Science Foundation of ChinaProject(2018YFC1900505) supported by the National Key R&D Program of China
文摘A novel method for the separation and reclamation of vanadium and chromium from acidic solution was proposed. The principle for the separation is based on selective complexation. In specific, V(V) can be complexated by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(Ⅲ) remained in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(Ⅲ)-bearing solution can be reached by decomplexation and neutralization, respectively. The kinetics of the complexation reaction was studied. In addition, the precipitation ratio of vanadium reached 97% and the loss of chromium was less than 4% after process optimization. The complexing agent could be regenerated with a high ratio of 99.5%. The method was successfully applied to treating chromium-vanadium-bearing slag produced in conventional vanadium production industry. Vanadium and chromium could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%.
基金financially supported by the National Natural Science Foundation of China (Nos. 51404031 and U1608254)
文摘Accumulation of toxic ions in leachate is one factor limiting bioleaching applications. The effect of fluoride ions on the growth of bioleaching microorganisms has been extensively emphasized. In this study, HF is found to be the toxic form of fluoride that affects the bacterial activity under acidic conditions. The added aluminum could compete with H^+ to complex with F-, thus significantly decrease the concentration of HF and finally reduce the toxicity of fluoride to bacteria. When F^-/Al^(3+)concentration ratio is 0.5:1.0, Fe^(2+) oxidation rate could reach 0.167 g·L^(-1)·h^(-1), close to that of the biotic control group(0.195 g·L^(-1)·h^(-1)). The competitive complexation mechanism of fluoride by AlF_n^(3-n) results in stability constants of AlF_n^(3-n) complex(7.00) that are larger than those of HF(3.18). The F^-/Al^(3+) concentration ratio in the medium could affect the speciation of AlF_n^(3-n) complex.With the decrease in F^-/Al^(3+) concentration ratio, the coordination numbers of AlF_n^(3-n) decrease. Finally, the feasibility of fluoride detoxification by aluminum ion is verified. This work has meaningful implications for fluoride-containing bacterial bioleaching systems.
